<?php
/**
 +----------------------------------------------------------
 * 字符串截取，支持中文和其他编码
 +----------------------------------------------------------
 * @static
 * @access public
 +----------------------------------------------------------
 * @param string $str 需要转换的字符串
 * @param string $start 开始位置
 * @param string $length 截取长度
 * @param string $charset 编码格式
 * @param boolean|string $suffix 截断显示字符
 * @param int $repeat 截断显示字符的重复次数
 +----------------------------------------------------------
 * @return string
 +----------------------------------------------------------
 */
function msubstr($str, $start=0, $length, $charset="utf-8", $suffix=false,$repeat=false)
{
    if(function_exists("mb_substr")){ 
		if($suffix){ 
			if($repeat){
				for($i=0;$i<$repeat;$i++){
					$suffix.=$suffix;
				}
			}
			return mb_substr($str, $start, $length, $charset).$suffix;
		}else{
			return mb_substr($str, $start, $length, $charset); 
		}
	}elseif(function_exists('iconv_substr')) {
		if($suffix){
			if($repeat){
				for($i=0;$i<$repeat;$i++){
					$suffix.=$suffix;
				}
			}
			return iconv_substr($str,$start,$length,$charset).$suffix;
		}else{
			return iconv_substr($str,$start,$length,$charset);
		}
    }
    $re['utf-8']   = "/[\x01-\x7f]|[\xc2-\xdf][\x80-\xbf]|[\xe0-\xef][\x80-\xbf]{2}|[\xf0-\xff][\x80-\xbf]{3}/";
    $re['gb2312'] = "/[\x01-\x7f]|[\xb0-\xf7][\xa0-\xfe]/";
    $re['gbk']    = "/[\x01-\x7f]|[\x81-\xfe][\x40-\xfe]/";
    $re['big5']   = "/[\x01-\x7f]|[\x81-\xfe]([\x40-\x7e]|\xa1-\xfe])/";
    preg_match_all($re[$charset], $str, $match);
    $slice = join("",array_slice($match[0], $start, $length));
    if($suffix) return $slice."…";
    return $slice;
}